There are various problems associated with road transport. Among these problems are road accidents caused by human-related factors, such as tiredness, loss of control, a slow reaction time, limited field of view, insufficient maintenance of distance between vehicles, and inattention to traffic signs. A further transport-related problem is that of loss of time which may be caused by slow driving speed due to weather conditions, road conditions, visibility, and traffic congestion, for example. Unfamiliarity with the route may also cause a loss of time.
Apart from the inconvenience which may be caused by any of the above factors, these factors also represent a huge economic burden on developed society. If for these reasons alone, it would be desirable to provide an automated traffic system which substantially reduced the above problems.
During recent years the development of automated traffic systems has received increased attention, and substantial effort has been invested in trying to find a solution to problems such as those outlined above.
Two articles, entitled `The Intelligent Vehicle-Highway Systems Program in the United States` and `RTI/IVHS on European Highways` appear in the ITE 1993 Compendium of Technical Papers. These articles give a general overview of programs that are being developed and the aims of these programs, in the United States and Europe.
These programs, which relate to IVHS (intelligent vehicle-highway systems), are concerned with a wide range of different aspects of automation, such as, automatic vehicle identification for purposes of automatic tolling on toll roads; relaying of up-to-date information to drivers in order to improve their decision-making ability; and automatic driving systems.
Among various systems that have been developed are the following:
satellite-based vehicle navigation systems; PA1 traffic management systems based on a local and international integrated sensing and communications systems for passing information to drivers on road and traffic conditions, and for controlling traffic lights and electronic signs; PA1 two-way communications systems with drivers via radio beacons and transponders located by the side of the road or beneath it--these systems can automatically identify vehicles and broadcast thereto a wide range of different types of information, such as navigational instructions, traffic conditions, and the like; and PA1 automatic driving based on an on-board computerized control system, and on radio connection between vehicles and sensing devices for measurement of the inter-vehicle distance, wherein travel is carried out in `platoons`, wherein each platoon has predetermined travel and communication procedures. Platoon-oriented systems are described in a paper entitled `Sketch of an IVHS Systems Architecture`, published by the Institute of Transportation Studies of the University of California, Berkeley. PA1 the first level includes vehicle mounted on-board control and data exchange apparatus; and PA1 the second level includes a plurality of the road-based units arranged in series along each segment such that each road-based unit located along a selected travel route is operative, in turn, to establish two-way communications with the on-board control and data exchange apparatus of each vehicle traveling therepast. PA1 a transceiver, antenna apparatus for facilitating communications between the on-board units and the transceiver apparatus, and data processing apparatus. The data processing apparatus is associated with the transceiver apparatus, and is operative to receive data from and to send data to the on-board units, for exchanging data with an associated segment control unit via the parallel communications apparatus. The data processing apparatus is further operative to process data received from the on-board units and from the associated segment control unit. PA1 a transceiver for communicating with each of the plurality of road-based units in series while traveling therepast; PA1 data processing apparatus connected to the transceiver apparatus; and PA1 control apparatus, connected to the data processing apparatus for selectably controlling and sensing any of a predetermined plurality of vehicle operating functions in response to signals received by the transceiver apparatus from the road-based units.
While each system has its advantages and disadvantages, none of the systems known to the present Applicant constitutes a comprehensive answer to the problems outlined above.
An indication of the state of the art is provided by published PCT application no. PCT/US91/08892, publication no. WO 92/09941, entitled "Downward Compatible AGV System and Methods." This publication discloses an automated guided vehicle (AGV) control system which is downward compatible with existing guidewire systems providing both guidewire navigation and communication and guidance and wireless communication between a central controller and each vehicle, Autonomous vehicle navigation comprises travel over paths marked by update markers which may be spaced well apart, such as 50 feet (about 16 m).
Redundant measurement capability comprising inputs from linear travel encoders from the vehicle's drive wheels, position measurements from update markers, and bearing measurements from a novel angular sensing apparatus, in combination with the use of a Kalman filter, allows correction for navigation and guidance errors caused by such factors as angular rate sensor drift, wear, temperature changes, aging, and early miscalibration during vehicle operation. The control system comprises high frequency two-way data transmission and reception capability over the guidewires and via wireless communications. The same data rates and message formats are used in both communications systems. The above-outlined system is intended for purpose-built vehicles used in a warehouse situation. Accordingly, while addressing certain points of automated control of vehicles, it does not provide a solution to the various transport related problems discussed herein.
The following patent publications are also known: EP482424, EP229669, WO8200122 and EP367527. These publications describe systems that are intended for controlling vehicles in limited, defined areas, such as on factory floors, in the area of production lines, warehouses and the like. These systems include several dozen vehicles that travel in predetermined fashion along fixed routes, with fixed stopping places or stations, and which travel over a distance of between several dozen meters and several kilometers.
The operating principles of the systems described in above four documents do not permit management of a transport system on a large, substantially unlimited scale. The main reason for this, common to all these systems, is the fact that each system employs a vehicle communications and control system which employs a single central computer which manages all of the users, and all of the communications. To the best of our knowledge, no single computer exists which is capable of handling the tasks of continuous, real-time vehicle control, in a transport system encompassing possibly many millions of vehicles. It is thus apparent that none of these systems is either intended or presumes to be capable of managing a large scale transport system.
U.S. Pat. No. 4,361,202 describes a transport system that may contain millions of vehicles, but it is based on a single central computer, with its inherent drawbacks, as discussed above. Furthermore, no continuous communications exist between this system and the vehicles `controlled` thereby. System to vehicle communications are established at commencement of a journey only, by means of a radio-telephone link to the control center operated by a vehicle driver, so as to receive details of a recommended route, including driving directions that are recorded in the memory of a computer in the vehicle. Subsequently, unless the driver initiates further communication with the control center, no communications occur until the end of the journey. The vehicle drives itself in accordance with the route plan stored in its computer memory, and, further, in accordance with information provided by transponders along the route that provide to the vehicle information concerning the conditions and physical parameters at the transponder locations, rather than information particular to any specific vehicle traveling therepast.
This operating principle is based on the assumption that no changes will occur (or be required) and that the transport system will behave in practice exactly as planned--an assumption which, it is submitted, is totally inconsistent with modern driving conditions.
This system employs feedback from magnetometers or radar for detection of the speed and type of vehicles traveling along different routes. The system is not provided with any feedback in terms of the location of any particular vehicle or in terms of its mechanical/safety state, and is thus incapable of controlling vehicles individually, relating to vehicles as part of a mass only. Accordingly, it does not provide continuous and real time control of any specific vehicle.